ABSTRACT
There is a range of medical conditions, which include acute organ failure, bacterial and viral infection, and sepsis, that result in overactivation of the inflammatory response of the organism and release of proinflammatory cytokines into the bloodstream. Fast removal of these cytokines from blood circulation could offer a potentially efficient treatment of such conditions. This study aims at the development and assessment of novel biocompatible graphene-based adsorbents for blood purification from proinflammatory cytokines. These graphene-based materials were chosen on the basis of their surface accessibility for small molecules further facilitated by the interlayer porosity, which is comparable to the size of the cytokine molecules to be adsorbed. Our preliminary results show that graphene nanoplatelets (GnP) exhibit high adsorption capacity, but they cannot be used in direct contact with blood due to the risk of small carbon particle release into the bloodstream. Granulation of GnP using poly(tetrafluoroethylene) as a binder eliminated an undesirable nanoparticle release without affecting the GnP surface accessibility for the cytokine molecules. The efficiency of proinflammatory cytokine removal was shown using a specially designed flow-through system. So far, GnP proved to be among the fastest acting and most efficient sorbents for cytokine removal identified to date, outperforming porous activated carbons and porous polymers.
ABSTRACT
MXenes are a rapidly growing class of 2D transition metal carbides and nitrides, finding applications in fields ranging from energy storage to electromagnetic interference shielding and transparent conductive coatings. However, while more than 20 carbide MXenes have already been synthesized, Ti4N3 and Ti2N are the only nitride MXenes reported so far. Here by ammoniation of Mo2CTx and V2CTx MXenes at 600 °C, we report on their transformation to 2D metal nitrides. Carbon atoms in the precursor MXenes are replaced with N atoms, resulting from the decomposition of ammonia molecules. The crystal structures of the resulting Mo2N and V2N were determined with transmission electron microscopy and X-ray pair distribution function analysis. Our results indicate that Mo2N retains the MXene structure and V2C transforms to a mixed layered structure of trigonal V2N and cubic VN. Temperature-dependent resistivity measurements of the nitrides reveal that they exhibit metallic conductivity, as opposed to semiconductor-like behavior of their parent carbides. As important, room-temperature electrical conductivity values of Mo2N and V2N are three and one order of magnitude larger than those of the Mo2CTx and V2CTx precursors, respectively. This study shows how gas treatment synthesis such as ammoniation can transform carbide MXenes into 2D nitrides with higher electrical conductivities and metallic behavior, opening a new avenue in 2D materials synthesis.
